Ultrasound discriminates patients with hip fracture equally well as dual energy X-ray absorptiometry and independently of bone mineral density

Abstract

We measured the heels of 43 women who had recently sustained a hip fracture and 86 age matched controls, using an Achilles® ultrasound device. Average BUA, SOS, and Stiffness were significantly lower in fractured patients (p < 0.0001). We also estimated ultrasound parameters for patients as a function of controls and found the mean BUA to be −1.09 SD compared with controls, the mean SOS −0.89 SD, and the mean Stiffness −0.98 SD. Femoral BMD measured at the neck, Ward's triangle, and the trochanter with a DPX Plus® was also significantly lower in fractured patients (p < 0.0001). The increased risk of hip fracture associated with low ultrasound values was estimated with logistic regression analysis for each bone parameter, adjusted for height and weight. The adjusted regression coefficients associated with BUA, SOS, Stiffness, and BMD were all significant (p < 0.0001) demonstrating the influence of all ultrasound and DXA parameters on the risk of hip fracture. After adjusting the logistic regressions for BMD neck, BUA, SOS, and Stiffness were still significant independent predictors of hip fracture. Sensitivity and specificity of all measures were analyzed with the area under the ROC curve which were for BUA, 0.77 ± 0.04; for SOS, 0.75 ± 0.04; for Stiffness, 0.78 ± 0.04; and for BMD, 0.74 ± 0.04. We determined the range for the best compromise between sensitivity and specificity of BUA, 97–98 dB/MHz; SOS, 1482–1487 m/s; Stiffness 59–62% Young Adult; and of BMD, 0.64–0.69 g/cm. The area under the ROC curves of BUA, SOS, Stiffness, and DXA were compared and no statistically significant difference was found. Patients with trochanteric fractures had significantly lower ultrasound parameters than those with cervical fractures (SOS and Stiffness p = 0.001, BUA p = 0.009), whereas no significant difference was found for DXA parameters (BMD neck, BMD Ward, and BMD trochanter p ≥ 0.5). Some previous studies showed a lower bone density in patients with trochanteric fractures and suggested that the two types of fractures might correspond to a different process. Our results suggest that ultrasound is better correlated to the type of fracture than DXA, discriminates subjects with hip fracture equally well as DXA, and does indeed provide an indication of fracture risk independent of BMD.